There are many variations on simple cycle gas turbines, which can provide features such as small size, light in weight, reliability, simplicity, or other attributes. Emphasis is often placed on performance and power density, and achieving these objectives through use of known technologies and design principles for compressors, turbines, combustors, heat exchangers, and technology from related conventional material sciences has been attempted.
Component research and development efforts over recent years have served well to define advanced levels of aerodynamic and thermodynamic component efficiency. By combining these advances with similar gains in material sciences and cooling technologies, capability now exists to design for high stage pressure ratios and high operating temperatures. Nevertheless, the prior art increases in component technology still leaves room for improving the utility of these engines, while also increasing the number of applications in which these systems may be used.
Numerous system modifications have been proposed previously for increasing the performance of gas turbine engines, such as reheat cycles, humid air cycles, inlet cooling, and inlet water fogging. Each of these approaches offers benefits, but at the expense of additional system complexity and cost. One especially relevant modification is the use of recuperation, with or without intercooling, particularly for small gas turbine engines. Recuperated microturbines have significantly higher efficiency than unrecuperated microturbines, but the cost, size, and weight of the system are increased substantially. A recuperated microturbine has also been integrated with a vapor absorption refrigeration system in order to maintain high efficiency, utilizing waste heat extracted from the turbine exhaust to drive the refrigeration system. The difficulties with the current state of the art are that the system cost, size, and weight are increased substantially, the emissions levels are not improved, and water is not inherently extracted from the exhaust.